Systems and methods for constructing a synthetic anatomical model with predetermined anatomic, biomechanical, and physiological properties

ABSTRACT

A computing device and a three-dimensional printer are disclosed. Data associated with reference anatomical properties is accessed by the computing device to generate a set of 3D printing files. The 3D printing files are compiled using the computing device to generate a printing model defining an anatomic orientation corresponding to the reference anatomical properties. Printing parameters and materials for the printing model are configured referencing experimentally derived datasets that define predetermined settings for the printing parameters and materials that are suitable for constructing a synthetic anatomical model with properties related to the reference anatomical properties. A synthetic model is printed using the printing parameters and materials as configured. The printing parameters and materials may be modified as desired subsequent to biomechanical testing of the model. Additional synthetic anatomical components may be added to or included with the model during post-processing, or before or during formation of the model.

CROSS REFERENCE TO RELATED APPLICATIONS

This Patent Application is a continuation-in-part of and claims priorityunder 35 U.S.C. § 120 to U.S. patent application Ser. No. 16/489,431,entitled “SYSTEMS AND METHODS FOR CONSTRUCTING A SYNTHETIC ANATOMICALMODEL WITH PREDETERMINED ANATOMIC, BIOMECHANICAL, AND PHYSIOLOGICALPROPERTIES,” filed Aug. 28, 2019, which is related to and claimspriority under 35 U.S.C. § 371(c) to the national stage entryapplication claiming priority under 35 U.S.C. § 371(c) toPCT/US2018/035233, entitled “SYSTEMS AND METHODS FOR CONSTRUCTING ASYNTHETIC ANATOMICAL MODEL WITH PREDETERMINED ANATOMIC, BIOMECHANICAL,AND PHYSIOLOGICAL PROPERTIES,” filed May 30, 2018, which is related toand claims priority under 35 U.S.C. § 119(e) to U.S. Provisional PatentApplication No. 62/512,243, entitled “METHOD FOR CONSTRUCTING ASYNTHETIC SPINE MODEL WITH HIGH ANATOMIC AND BIOMECHANICAL FIDELITY TO ACADAVERIC SPINE MODEL,” filed May 30, 2017; U.S. Provisional PatentApplication No. 62/518,653, entitled “METHOD FOR CONSTRUCTING ASYNTHETIC SPINE MODEL WITH HIGH ANATOMIC AND BIOMECHANICAL FIDELITY TO ACADAVERIC SPINE MODEL,” filed Jun. 13, 2017; U.S. Provisional PatentApplication No. 62/591,241, entitled “SYSTEM AND METHOD FOR CONSTRUCTINGA SYNTHETIC SPINE MODEL WITH ANATOMIC, BIOMECHANICAL, AND PHYSIOLOGICALFIDELITY TO A SPINE MODEL,” filed Nov. 28, 2017; U.S. Provisional PatentApplication No. 62/589,756, entitled “ SYSTEM AND METHOD FOR 3-D PRINTEDOSTEOTOMY MODELS,” filed Nov. 22, 2017; U.S. Provisional PatentApplication No. 62/589,788, entitled “SYSTEM AND METHOD FOR 3-D PRINTEDMODELS,” filed Nov. 22, 2017; U.S. Provisional Patent Application No.62/589,733, entitled “Systems and Methods for Fluoroscopic analysis of asynthetic spine model made of variable 3D-printed materials,” filed Nov.22, 2017; U.S. Provisional Patent Application No. 62/589,768, entitled“SYSTEM AND METHOD FOR 3-D PRINTED MODELS FOR PEDICLE SCREW INSERTION,”filed Nov. 22, 2017; and U.S. Provisional Patent Application No.62/589,780, entitled “SYSTEM AND METHOD FOR 3-D PRINTED MODELS,” filedNov. 22, 2017; all of which are fully incorporated by reference hereinfor all purposes.

FIELD

The present disclosure generally relates to systems and methods forcreating synthetic anatomical models. More specifically, the presentapplication describes systems and methods for configuring an apparatuscomprising a three-dimensional printer and computing device to constructa base synthetic anatomical model with specific predefined anatomic,biomechanical, and physiological properties, which may be supplementedwith additional synthetic anatomical components before, during, orpost-processing.

BACKGROUND

Synthetic spine models and other anatomical models are critical tosurgical education, patient education, the development and testing ofnew surgical treatment strategies, the development and testing of newdevices for use in the treatment of spinal disorders, and as a researchplatform in spine biomechanical studies. Cadaveric spines are currentlyused as a standard educational and research platform for most of theabove purposes. Cadaveric spines come with many limitations, however,that make their utility in surgical education, biomechanical research,and/or with new device testing platform highly limited.

Disadvantages of cadaveric spine models include their expense,difficulty in acquisition (via donors at the time of death), humantissue handling restraints and institutional requirements for cadaverictesting, risk to laboratory personnel when handling human tissue,inability (or very high difficulty) in obtaining models of specificpathologies, and high variability in biomechanical performance betweenspecimens (thought to be due to variations in preservation technique,age of cadaveric specimen, and bone and soft tissue quality of donor atthe time of death) which results in wider result variability duringbiomechanical testing. This wider result variability must be overcome byusing larger numbers of cadavers during testing, further increasing thecost, tissue handling requirements, and subsequent risks.

It is with these observations in mind, among others, that variousaspects of the present disclosure were conceived and developed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram illustrating a system forconfiguring an apparatus comprising a three-dimensional printer andcomputing device for constructing a synthetic anatomical model withspecific predefined anatomic, biomechanical, and physiologicalproperties.

FIG. 2A is an exemplary process flow for utilizing the system of FIG. 1to construct a synthetic anatomical model with specific predefinedanatomic, biomechanical, and physiological properties.

FIG. 2B is a radiograph view of a reference anatomical component (spinalsegment).

FIG. 2C is an image of a synthetic spinal segment printed to mimiccertain predefined anatomic, biomechanical, and physiological propertiesof the reference spinal segment of FIG. 2B.

FIG. 2D is a radiograph image of the reference spinal segment of FIG. 2Bafter surgical correction.

FIG. 2E is an image of the synthetic spinal segment of FIG. 2C aftersimulated surgical correction.

FIG. 3 is a side view of a synthetic spine model constructed accordingto the method described in FIG. 2A and discussed herein.

FIG. 4 is a lateral view of an X-ray taken of the same spine modelreferred to in FIG. 3 after pedicle screw placement.

FIG. 5 is an anterolateral view of the same model in FIG. 3,demonstrating the different 3D printed materials representing andbiomechanically performing as bone (white), anterior longitudinalligament (black), and annulus fibrosis (black).

FIG. 6 is a posterior view of the same model in FIG. 3, demonstratingthe different 3D printed materials representing and biomechanicallyperforming as bone (white), and posterior longitudinal ligament (black).In this model the facet joints have been removed to simulate a posteriorcolumn osteotomy.

FIG. 7 is an image illustrating biomechanical testing of a vertebralbody model, specifically axial screw pullout strength testing. Thistesting contributed to the experimentally derived protocols forconfiguring or selecting specific print parameters to mode specifichealthy or diseased bone states.

FIG. 8 is a lateral view of the same spine model referred to in FIG. 3after pedicle screw insertion and biomechanical testing of pedicle screwand intervertebral disc compression.

FIG. 9 is a lateral X-ray taken of the same spine model referred to inFIG. 8 at the time of biomechanical testing of pedicle screw andintervertebral disc compression.

FIG. 10 is an image illustrating a 3D printed vertebral body model withpre-determined cannulation trajectories of the vertebral pedicle.

FIG. 11 is an image illustrating a synthetic vertebral body model thatis being printed to include pedicle cannulation trajectories.

FIG. 12 is a top view illustrating a vertebral body associated with asynthetic spine model according to the present inventive concept wherearrows denote the dense shell layers and less dense in-fill.

FIG. 13 is an axial view of a synthetic L5 vertebral body model understandard fluoroscopy and constructed using the methods described herein.

FIG. 14 is a photograph of a synthetic spine model constructed using themethods described herein with a horizontal orientation.

FIG. 15 is another photograph of a synthetic spine model constructedusing the methods described herein with a vertical orientation.

FIG. 16A-16C are box plot summaries demonstrating the effect of materialtype on the tested parameters.

FIG. 17A-17I are box plot summaries demonstrating the effect of materialand in-fill on the tested parameters.

FIG. 18 is an image demonstrating artificial bleeding of synthetic bone.

FIG. 19 is an image demonstrating a synthetic thecal sac.

FIG. 20 is an image demonstrating printed conductive 3D synthetic neuralelements or nerve roots.

FIG. 21 is an image demonstrating conductive synthetic nerve roots addedto a model after printing.

FIG. 22 is an image demonstrating synthetic 3D printed psoas muscle withnerve roots running through it.

FIG. 23 is an image demonstrating arterial blood vessels added to asynthetic anatomical model.

FIG. 24 is a microscopic surgical view of an image demonstratingradiolucent soft tissue deployed with an anatomical model.

FIG. 25 is an image demonstrating synthetic ligamentum flavum integratedinto a model.

FIG. 26 is an image demonstrating a synthetic spinal segment withsynthetic collagen simulating a periosteum tissue layer covering thebone.

FIG. 27 is a simplified block diagram illustrating an example of acomputing system that may implement various services, systems, andmethods discussed herein.

FIG. 28A is an image of a base constructed to support and guide movementof a synthetic anatomical model where the model is in an extendedposition.

FIG. 28B is an image of a base constructed to support and guide movementof a synthetic anatomical model where the model is in a flexed position.

FIG. 29A is an image demonstrating distinct and less fused layers of a3D printed synthetic spinal segment.

FIG. 29B is an image demonstrating less distinct layers in a 3D printedsynthetic spinal segment that are fused together by application of asolvent.

Corresponding reference characters indicate corresponding elements amongthe view of the drawings. The headings used in the figures do not limitthe scope of the claims.

DETAILED DESCRIPTION

An ideal platform for performing surgical education (e.g., for medicalstudents, physicians, medical-industry personnel, patients, etc.),biomechanical testing, and new medical device testing may have at leastthe following features: comprised of synthetic materials with indefiniteor very long shelf life; very high fidelity to human tissue in terms ofgross anatomy, radiographic anatomy, biomechanical performance ofsynthetic bone material, and biomechanical performance of synthetic softtissue materials; ability to construct this platform to mimic any normalor pathological state of anatomy; and ability to include in the platformcertain features that allow the platform to mimic physiologicalfunctions including but not limited to bleeding, electricalconductivity, leakage of spinal fluid, and monitoring of pressureswithin certain areas of the model.

Accordingly, in view of the aforementioned and other observations, thepresent disclosure relates to an inventive system and methods forconstruction of anatomical models which may include synthetic spinemodels and/or other synthetic anatomical components. Comprehensiveresearch and testing methods were conducted to generate experimentallyderived datasets that have been found to be advantageous towardsconfiguring a computing device and/or a three-dimensional (3D) printerfor forming customized synthetic anatomical base models, such as asynthetic 3D-printed vertebra base model or other spinal segment thatexhibits high anatomical, physiological, and biomechanical fidelityrelative to a cadaveric vertebra or other bone tissue, or otherwiseexhibits characteristics that conform with specific predeterminedproperties. Specifically, in one embodiment, image data may be extractedor generated from a plurality of sample (living or cadaveric) vertebralsegments. Each of the sample vertebral segments may exhibit or includevarious different biomechanical, anatomical, and/or physiologicalproperties such that the integrated image data is as comprehensive asdesired; i.e., covers a suitable range of possible spinal segmentproperties. The integrated image data of the sample vertebral segmentsmay then be compiled into one or more 3D printing files, and 3D modelsof the sample vertebral segments may be printed. The 3D models of thesample vertebral segments may then be subjected to various biomechanicaltests as described herein to generate experimentally derived datasetsdefining relationships between properties associated with the samplevertebral models and materials and printing parameters for a 3D printeror additive manufacturing device. In other words, the experimentallyderived datasets define or are otherwise informative as to theparticular configuration of suitable materials and printing parametersunique for subsequently generating (by 3D printing or additivemanufacturing) synthetic spine models or other anatomical componentswith certain properties corresponding to various examples of the samplevertebral segments (having different conditions, anatomicalorientations, etc.).

The experimentally derived datasets may then be leveraged to construct asynthetic spinal segment model or other anatomical model with desiredproperties of any of the sample models (or properties from other sampleinformation). For example, to generate a synthetic spinal model with ananatomical orientation similar or identical to a particular form ofscoliosis, an experimentally derived dataset may be leveraged that hasbeen previously generated from a sample cadaver model. Theseexperimentally derived datasets can inform certain aspects of the3D-printing process, including but not limited to the material used, theshell thickness, or the in-fill density, to generate a model withcertain bony biomechanical properties. Similarly, an image dataset of apatient or cadaver with a certain type of scoliosis can be converted toa 3D file for modeling of that specific scoliotic anatomy. Printparameters, disc heights, facet joint modifications, and/or other 3Dfile or 3D printer modifications can then be employed to create a modelwith very high anatomical and biomechanical fidelity to a natural(.e.g., human or otherwise) spine with the same scoliotic curve. Inother words, printing parameters and materials for a given 3D printingfile may be configured or otherwise modified according to theexperimentally derived datasets to construct a synthetic spinal segmentwith an anatomic orientation exhibiting the same or similar form ofscoliosis. Accordingly, leveraging the experimentally derived datasetsaccommodates the 3D printing of a synthetic spine or other anatomicalmodel that exhibits a set of desired or predetermined anatomical,biomechanical, and physiological characteristics.

In some embodiments, leveraging similar testing methods or otherresearch as described, other anatomical components may be constructedand may include synthetic blood vessels, a synthetic thecal sac,synthetic muscle, and synthetic periosteum, and other synthetic mimicsof anatomical components in addition to the 3D printed synthetic model,as further described herein. Referring to the drawings, one embodimentof a system for configuring an apparatus comprising a three-dimensionalprinter and computing device to construct a synthetic anatomical modelwith specific predefined anatomic, biomechanical, and physiologicalproperties is illustrated and generally indicated as 100 in FIGS. 1-27.

Referring to FIG. 1, a non-limiting exemplary system 100 forconstruction of a synthetic anatomical model (such as a synthetic spinalsegment) is shown. The system 100 may generally include a printingapplication 102 executed by a computing device 104, and a 3D printer 106in operable communication with the computing device 104 (by wiredconnection or wirelessly connected) via a network 108. The printingapplication 102 and the computing device 104 may be configured to issuecommands to the 3D printer 106 for constructing a synthetic spinesegment or other anatomical model with predetermined properties, asdescribed herein, among other features.

The computing device 104 may include one or more of a server,controller, a personal computer, terminal, workstation, laptop, mobiledevice, tablet, mainframe, or other such computing device configured bythe application 102 or otherwise to implement functionality associatedwith 3D printing or additive manufacturing described herein. Theprinting application 102 may include or otherwise have access tofunctionality associated with one or more 3D imaging and/or printingsoftware packages, specially configured or otherwise, and may include,e.g., Blender, Cura, OpenSCAD, Slic3r, 3D Slash, Design SparkMechanical, Mimics, Simplify3D, and the like. The printing application102 may be configured to convert images (high-resolution or otherwise)into a 3D modeling file, extract features of the images associated withdesired anatomical components, and convert the features to .stl formator other printing file format as printing instructions. In addition, theprinting application 102 may be further configured to transmit theinstructions from the computing device 104 to the 3D printer 106 toprint a synthetic model as described herein. Aspects of the computingsystem 100 and/or the printing application 102 may be provided usingplatform as a service (PaaS), and/or software as a service (SaaS) usinge.g., Amazon Web Services, or other distributed or decentralizedsystems. The network 108 may include the Internet, an intranet, avirtual private network (VPN), a local area network (LAN), a wide areanetwork (LAN), a peer-to-peer network, a cloud, and the like. In someembodiments, a cloud (not shown) may be implemented to execute one ormore components of the computing system 100.

As indicated, the computing device 104 may be in operable connectionwith or may otherwise have access to a database 110. The database 110may store experimentally derived datasets 112 and other associatedinformation as described herein. Data from the datasets 112 stored inthe database 110 may accessed by the application 102 and computingdevice 104 in real time or otherwise as desired, and may be updated asadditional experimentally derived datasets 112 are generated or modifiedusing the methods described herein.

As further indicated, the computing device 104, the printing application102, the 3D printer 106, and the database 110 (including theexperimentally derived datasets 112), may collectively define anapparatus 114. Configuring the apparatus 114 as described hereinaccommodates the construction of a synthetic anatomical model 116 withany number of specific predetermined anatomic, biomechanical, andphysiological properties. In some embodiments, the synthetic anatomicalmodel 116 may define a base synthetic anatomical model, which may besupplemented with additional synthetic components before, during, orsubsequent to a post processing step 150 as further described herein.

In addition, at least some features of the printing application 102 maybe made available to a plurality of user devices 120 in communicationwith the computing device 104 via the network 108. The plurality of userdevices 120 may include, without limitation, at least one of acontroller, a personal computer, terminal, workstation, portablecomputer, laptop, mobile device, tablet, phone, pager, or multimediaconsole. Any one of the plurality of user devices 120 may be implementedto e.g., submit information to the computing device 104 for modifying orsupplementing the database 110, requesting a particular syntheticanatomical model, and the like.

Referring to FIG. 2A, with continuing reference to FIG. 1, a processflow 200 is shown for implementing the system 100 to construct thesynthetic anatomical model 116 with specific predetermined anatomic,biomechanical, and physiological properties as desired leveraging theexperimentally derived datasets 112. As shown in block 202, a referenceanatomical component, such as a spinal segment, pelvic bone, temporalbone, or desired anatomical properties may first be selected, accessed,or identified. The reference anatomical component and/or properties maybe selected from any number of data sources and may be associated withor represent any number of applications. For example, the referenceanatomical component may include or may be representative of a referencespinal segment 250 (shown in FIG. 2B) of a particular patient that isscheduled for a spinal fixation procedure and application of a spinalfixation construct. In this example, the reference spinal segment 250 ofthe patient may include various particular anatomical, physiological,and biomechanical properties, and it may be desirable to generate thesynthetic anatomical model 116 with properties similar to the referencespinal segment 250 of the patient in order to mimic or replicate thescheduled spinal fixation procedure by conducting one or more trialspinal fixation procedures to using one or more of the syntheticanatomical model 116 (modeled to mimic the reference spinal segment250), in order to, e.g., provide the surgeon with surgical preparationtime and training, and to proactively identify possible failure pointsof the natural reference spinal segment 250. Such preparation time andthe ability to identify possible failure points can dramaticallyincrease the probability of a successful procedure and generallyincrease confidence with the surgeon.

As another example, the reference spinal segment 250 or desiredproperties may be selected based on a particular training applicationdesired for spinal surgeons. Specifically, the synthetic anatomicalmodel 116 may be printed to help surgical trainees understand certainaspects of surgical anatomy, or to better perform certain surgicalskills and techniques. In this manner, the synthetic anatomical model116 may be capable of replicating the physical properties of cadavericspines for the purposes of both resident education and biomechanicaltesting. This assists residents to learn complex spinal proceduresthrough hands-on surgical manipulation of a 3D-printed spine replicathat closely mimics the physical properties of the human vertebralcolumn. As demonstrated by these examples, a reference spinal segment ordesired anatomical properties may be selected from a cadaver, a livinghuman or other animal/mammal (e.g., companion animal for veterinaryapplications), or the properties may be individually selected, e.g., itmay be desired to print the synthetic anatomical model 116 with specificproperties (e.g., a particular bone density) that do not necessarilyconform to a specific cadaver or living animal. In some embodiments, theanatomical properties may be derived from non-human animals, such thatthe reference properties or reference anatomical components and thesubsequently generated synthetic model may be useful for veterinaryapplications; e.g., modeling portions of a canine's spine. The user maydecide what information is relevant to generate the desired syntheticanatomical model 116, such as a component that contains vascularanatomy, or artificial neural elements capable of conductingelectricity, or any standard healthy anatomy or any number ofpatient-specific disease states, with, e.g., anatomical andbiomechanical fidelity to that healthy or diseased-state. Specificexamples of properties that it may be desired to replicate (and mayultimately be replicated as described herein) with the syntheticanatomical model 116 may include range of motion or flexibility, bonemineral density, anatomical shapes, textures, and dimensions, blood lossthrough bone, bleeding from direct vessel injury, monitoring ofelectrical signals through synthetic neural elements, monitoring ofpressure in particular parts of the model such as the thecal sac toprovide feedback on potential for neural element injury during aparticular surgical maneuver, and radiographic feedback from the modelunder standard radiographic image processes such as fluoroscopy orcomputed tomography.

Referring to block 204 in FIG. 2A, in some embodiments, image data (notshown) associated with the reference anatomical component (e.g., thereference spinal segment 250) or the desired synthetic anatomical model116 and/or spinal segment properties may be generated or otherwiseaccessed by the printing application 102 and/or the computing device 104in preparation for 3D printing or additive manufacturing (which mayultimately be used to generate a 3D printable model for the syntheticanatomical model 116). In some embodiments, the image data may begenerated using a computer-aided design (CAD) package (separatelyimplemented or integrated within the printing application 102), and thegenerated image data may include one or more .STL files associated withstereolithographic CAD software (accessed or integrated with theprinting application 102). The image data may also include DICOM® datadefining a voxel-based morphometry of e.g., the reference spinal segment250, pixel-based imaging of the reference spinal segment 250, and thelike, which may be segmented or sliced. In some non-limitingembodiments, the user may access the image data through a visualizationtool such as a magnetic resonance image (“MRI”), a computed topography(“CT”), an X-ray, an ultrasound, or any other digital visualizationmethod applied to e.g., the reference spinal segment 250. In someembodiments, the image data may be generated using a 3D scanner orgeneral photogrammetry software applied to e.g., the reference spinalsegment 250. In some embodiments, the image data may be provideddirectly to the computing device 104 by tracking or scanning an image ofe.g., the reference spinal segment 250 in real time, or by downloading adigital image associated with the reference spinal segment 250 intomemory accessible to the computing device 104. The image data generatedusing any of the aforementioned scanning methods defines sequentialdigital layers associated with the shape and appearance of the referencespinal segment 250 or other reference anatomical component, whichsubsequently accommodates the creation of a 3D digital model (layer bylayer) based on such image data, as further described herein.

In other non-limiting embodiments, no digital visualization method maybe needed. To illustrate, the user may decide to compile a digital imagefrom artificially generated data representative of certain predeterminedanatomical properties desired by the user. For example, pre-generated 3Dmodels of spinal segments, or other data, may be used on their own orcombined with a digital visualization method. In addition, the imagedata can be compiled from multiple models of spinal segments frommultiple patients, or one patient over different time periods. Moreover,it should be considered that the method may be used to generate anycomponent of a human or non-human body. For example, it is alsocontemplated that this method may have use in the veterinary field aswell.

Referring to block 206, the components of the image data may be compiledwith, fed to, or otherwise accessed by the printing application 102 togenerate one or more 3D printing files (or additive manufacturing files)defining a 3D model of the reference anatomical component, such as thereference spinal segment 250. In one embodiment, a command hierarchy ofthe printing application 102 may be used. For example, a user may select“File”, then “Export” and then choose the “.stl” file format to convertthe image data to one or more STL (stereolithography) files. This mayalso be achieved automatically by functionality of the printingapplication 102 designed to execute hierarchy commands. In other words,the printing application 102 may be configured to generate one or more3D printing files, such as .STL files, based on the image data. The 3Dprinting files define a 3D printing model of e.g., the reference spinalsegment 250.

In other embodiments, the printing application 102 may further beconfigured to generate other types of 3D printing files representativeof a printing model of the reference spinal segment. For example, one ormore additive manufacturing files (AMF)s may be generated defining a 3Dprinting model of the reference spinal segment that may be applied foradditive manufacturing applications. Printing files associated withfused deposit modeling (FDM) may also similarly be generated andutilized.

In some embodiments, once the image data is compiled into one or more 3Dprinting files, data associated with the 3D printing files may beprocessed or examined for possible errors or adjustments and may berepaired as desired. For example, STL files may generally includeabnormalities or errors in the form of holes, incorrect orientation ofimage features, and the like. At this stage, a user may interact withthe printing application 102, or the application 102 may be programmedwith functionality to change the dimensions of the 3D printing model toe.g., adjust orientation of features of the 3D printing model, fill ingaps or holes or otherwise adjust such features, separate inadvertentlyfused components of the 3D printing model to more closely model thereference spinal segment 250, and the like. The user may also modify the3D printing model such that the model ultimately printed has either openor fused facet joints. In some embodiments, subsequent to anyadjustments to the 3D printing model applied at this stage, the 3Dprinting files may be processed to convert the files into digital layerswith instructions tailored specifically for specific 3D printers oradditive manufacturing components.

In addition, a user may select a region of interest of the 3D printingmodel; for instance, a region representing a lamina of the referencespinal segment 250, and alter its default value, or values defined bythe default 3D model as desired. The computing device 104 may furthercontinuously compare a selected pixel or voxer with its neighboringpixels or voxers to determine their location and characteristics formatching, and may be configured with (via the printing application 102or otherwise) with tools to morph or change parameters of the 3Dprinting model such that they are suitable for the user's purpose. Inone non-limiting embodiment, the desired shape and construction of thesynthetic anatomical model 116 can be simulated with just the user'sjudgement alone. Alternatively, the user may generate the 3D printingmodel based on a reference body, individual calculations, referencedata, or with a software algorithm that can identify and createparameters to the user's needs. Such an algorithm may be implemented inother steps of the disclosed method as well, and the computer softwarecan determine or calculate part of what the default 3D model should looklike.

Referring to block 208, printing parameters and materials associatedwith the 3D printing model may be configured, referencing theexperimentally derived datasets 112, so that the synthetic anatomicalmodel 116 may ultimately be constructed with properties that simulate orresemble the properties of the reference anatomical component, such asthe reference spinal segment 250 of block 202. The experimentallyderived datasets 112 may include intelligence about specificconfigurations or selections of materials and print parameters suitablefor constructing the synthetic anatomical model 116 with the desiredproperties of the reference spinal segment 250. Print parameters mayinclude, e.g., a number of print shells, in-fill percentage, filamentmaterial, extruder temperature, print orientation, and in-fill pattern,among others. Possible materials may include Acrylonitrile butadienestyrene (ABS), a plastic polymer; Nylon; Polylactic Acid (PLA); or other3D printing filaments such as Polyethylene terephthalate (PET);thermoplastic elastomer (TPE); thermoplastic polyurethane (TPU); highimpact polystyrene (HIPS); polyvinyl alcohol (PVA); carbon fiber,polycarbonate; wood; metals; or combinations thereof, or any otherdifferent types of known printer filaments suitable for replicatingaspects of the reference spinal segment 250 or other referenceanatomical component or predefined anatomical properties.

To illustrate, defects in the spine, such as osteopenia, may result inpockets of low bone density in the subject's spinal segment.Accordingly, it may be desired to build the synthetic anatomical model116 with pockets of low bone density along predetermined areas of themodel. Referencing the experimentally derived datasets 112, the printparameters and the materials may be configured based on theexperimentally derived datasets 112 to construct the syntheticanatomical model 116 to have a T-score of −1 or −2.5, or indeed whateverdensity is desired. In this way, a user may practice surgical techniquesrelated to osteopenia on the synthetic anatomical model 116 or use it assurgical prosthetic. In one non-limiting embodiment, one or more defaultprint parameters can be suggested by the printing application 102 andthen this default can be adjusted by the user to their preference suchthat it matches the desired dimensions, or properties of the patient orthe final design. As described herein, this may be accomplished byaltering the print parameters and materials selection for the print;these alterations including, but not limited to shape, porosity,composition, structure, in whole or part of the component.

Referring to block 210, once the 3D printing model has been sufficientlyadjusted as desired in block 206, and the print parameters and materialshave been configured in block 208, the printing application 102 maygenerate a set of executable printing instructions (not shown)compatible with the 3D printer 106 or other printing or additivemanufacturing device. The executable printing instructions may definethe 3D printing model and instruct the 3D printer 106 to utilize aparticular configuration of print parameters and materials settings andselections for printing the synthetic anatomical model 116.

The synthetic anatomical model 116 may then be printed with thepredetermined physiological, anatomical, and biomechanical propertiespreviously determined by configuring the materials and printingparameters described. Any number of different variations of thesynthetic anatomical model 116 may be printed (by way of the executableprinting instructions or otherwise) by leveraging the experimentallyderived datasets 112 to print the model to customized specifications asdesired for different applications. In one non-limiting embodiment, thedisclosed method of FIG. 2A may service to replace or amend the use ofcadaveric models in biomechanical testing. Unlike cadaveric models, themethod of the present inventive concept creates the synthetic anatomicalmodel 116 with components that are completely customizable, therebyreplacing the need to implement cadavers for biomechanical testing. Thecustomizable synthetic anatomical model 116 may correspond to thereference spinal segment and the 3D printable model generated from theimage data, or otherwise.

Referring again to FIG. 2B and referring to FIG. 2C, the (printed)synthetic anatomical model 116 may include a printed synthetic spinalsegment model 260 created using image data in the form of ahigh-resolution computed tomography of the same patient associated withthe reference spinal segment 250, and formed to resemble or mimic thereference spinal segment 250. The synthetic spinal segment model 260 maybe printed with different portions having different simulated/syntheticanatomical, physiological, or biomechanical properties. As shown, forexample, the synthetic spinal segment model 260 printed based on thereference spinal segment 250 may be printed to include at least a firstportion 262, a second portion 264, and a third portion 266. The firstportion 262 may be printed according to a first printing configuration(with e.g., certain materials and print parameters), the second portion264 may be printed according to a second printing configuration (withe.g., certain materials and print parameters which may differ from thematerials and print parameters of the first configuration), and thethird portion 266 may be printed according to a third printingconfiguration (with e.g., certain materials and print parameters whichmay differ from the materials and print parameters of the first/secondconfigurations). In other words, the synthetic spinal segment model 260may be printed with synthetic bone that mimics the bone of the referencespinal segment 250 with respect to gross anatomy, radiographic anatomy,and biomechanical performance when instrumented with pedicle screws. Thesynthetic spinal segment model 260 may also be printed withintervertebral discs (first portion 262), an anterior longitudinalligament (second portion 264), and a posterior longitudinal ligament(third portion 266) so that the relative flexibility of the syntheticspinal segment model 260 mimics the flexibility of the patientassociated with the reference spinal segment 250.

Referring to FIGS. 2D-2E, the synthetic anatomical model 116 may beutilized for training, preparation, or other applications such as thesimulation of surgical correction. In FIG. 2D, surgical correction hasbeen applied to the reference spinal segment 250 using a spinal fixationconstruct 272. Similarly, a spinal fixation construct 274 has beenapplied to the synthetic spinal segment model 260. The spinal fixationconstruct 272 may be the same or similar construct as the spinalfixation construct 274, so that surgical correction of the referencespinal segment 250 may be simulated using the synthetic spinal segmentmodel 260 and the spinal fixation construct 274. As shown, the remainingcurve left over after surgical correction has been applied to both ofthe reference spinal segment 250 and the synthetic spinal segment model260 is similar in value, which demonstrates that the synthetic spinalsegment model 260 has been constructed advantageously with similarproperties to that of the reference spinal segment 250 and thereforeprovides a suitable tool for education and surgical preparation.

As another specific example, referring to FIGS. 3-6, a non-limitingembodiment of a printed spinal segment 302 is illustrated that has been3D printed in parts or in whole using the method of FIG. 2A forconstructing an anatomical model with anatomic and biomechanicalfidelity to a cadaveric spine model. In this embodiment, the printedspinal segment 302 is constructed with biocompatible materialsconfigured to have physical and chemical properties that may enable thespinal segment 302 to be integrated with natural anatomy. Specifically,the printed spinal segment 302 includes printed components such asbiomechanically performing bone (304), anterior longitudinal ligament(306), and annulus fibrous (308). Each of these components may beprinted according to different specific configurations of printingmaterials and printing parameters in order to simulate natural anatomyfor each component. In addition, although not shown, the spinal segment302 may be printed with cavities configured to receive pedicle screws.It is noted that the segment need not be printed with completeanatomical accuracy to be suitable for use. The size, placement, andorientation of the pedicle screw cavities can be determined by the userin one non-limiting embodiment of this method, or indeed, it can bedecided by a computer algorithm. Other components can be incorporatedinto the pedicle screw cavity, such as threading, drill stops, and othercomponents or characteristics that the user could desire. It is alsocontemplated that a set or a single pedicle screw (not shown) could beprinted along with the spinal segment 302 and then be installed and heldin place by threading mechanisms, adhesives, fusing, or any otherattachment mechanism without departing from the scope of the disclosure.It is also considered, that the cavities could be drilled separately,and the pedicle screws or other components could be 3D printedindividually. With this model, the spinal segment 302 has had posteriorcolumn osteotomies performed upon it.

Ultimately, the user may design the structure and condition of thesynthetic anatomical model 116 according to any desired customizationsto accommodate factors such as cost, printing time, research purposes,or any other relevant purpose without departing from the scope of thedisclosure. For example, the synthetic anatomical model 116 may beprinted in a configuration that mimics a spinal deformity. In thisinstance, the testing procedure may be modified to include the sametechniques and instruments that would be customary for the specificintraoperative procedure, where the specific structure of the spinaldeformity may be abnormal in nature, in order to mimic patient spinaldeformities such as, but not limited to, spondylolisthesis andscoliosis. In addition, as described, many suitable variants of printingor building materials may be used. The user may modify, during theaforementioned steps of process flow 200 or after, the type of printingmaterial, the amount of printing material used, and any othercombination of parameters suitable for the user's needs. In addition,additives may be added to the printing reservoir of the 3D printer 106to impact the physical and chemical properties of the printed component.For example, anti-microbial solutions may be added to the printingmaterial so that the final synthetic anatomical model 116 may haveanti-microbial properties suitable for medical purposes. Moreover, themethod of process flow 200 may include supplementary printing processesto complete the printed synthetic anatomical model 116. To illustrate,the instant non-limiting method could include a stereolithographic step,a fused deposition modeling step, an electron beam additivemanufacturing step, a selective laser melting step, a selective lasersintering step, or any combination of these steps without departing fromthe scope of the disclosure. It is further contemplated that theprinting process described in FIG. 2A could take place in a sterileenvironment. For instance, the 3D printer 106 could be placed in a hood,or any environment with high-efficiency particulate air (HEPA)filtration configured to maintain sterility. The process flow 200 mayalso include a cooling step that allows the component to retain itsprinted shape.

Referring to block 212 of FIG. 2A, additional synthetic components(shown in FIGS. 18-26) may be constructed which may be integrated withthe synthetic anatomical model 116, or separately formed/used (asdescribed herein) for different applications during a post processingstep 150 or stage. The additional synthetic components formed during apost-processing step 150 may include a synthetic thecal sac, bloodvessels, nerve roots, various types of soft tissue, synthetic dermis,subcutaneous adipose tissue, paraspinal muscles, and supportive ligamentstructures of the spine or other components. The additional syntheticcomponents may be useful to simulate blood loss through synthetic bone(of the synthetic anatomical model 116), bleeding from direct vesselinjury, monitoring of electrical signals through synthetic neuralelements, monitoring of pressure in particular parts of the syntheticanatomical model 116 such as the thecal sac to provide feedback onpotential for neural element injury during a particular surgicalmaneuver, and provide radiographic feedback from the syntheticanatomical model 116 to under standard radiographic image processes suchas fluoroscopy or computed tomography. Such additional syntheticcomponents may be integrated or formed with the synthetic anatomicalmodel 116, during construction of the synthetic anatomical model 116,constructed separately before or after the construction of the syntheticanatomical model 116, and integrated with the synthetic anatomical model116 after formation.

Referring to block 214 of FIG. 2A, the synthetic anatomical model 116may undergo or be subjected to various testing procedures. For example,the synthetic anatomical model 116 may be subjected to controlled andmeasured forces, or to instrumentation, through a variable system ofcables, pulleys, belts, motors, and weights, all the while measuring thespinal range of motion using an optical tracking system, and the forcesapplied to the spine using mechanical force sensors. Variousmeasurements taken during testing may include, but are not limited to,the spine range of motion on flexion, extension, side-bending, and axialrotation, axial screw pullout strength, maximum torque on spinal screwinsertion, and numerous others. Analysis of these measures post-testingmay inform whether the 3D printing model for the synthetic anatomicalmodel 116 should be adjusted by e.g., applying modifications to theimage features of the 3D printing file, or by modifying print parametersand materials selection. As indicated in FIG. 2A, the process of testingthe synthetic anatomical model 116 and adjusting print settings may berepeated as desired.

FIGS. 7-9 illustrate testing of a vertebral body model 402 relative toat least one pedicle screw 403, specifically, axial screw pulloutstrength testing using a testing apparatus 404 having a vise grip 406.This testing contributed to the experimentally derived datasets 112 forconfiguring or selecting specific print parameters to mode specifichealthy or diseased bone states. The vise grip 406 is arranged toprovide a true axial force on the pedicle screw 403 as described herein.FIG. 8 is a lateral view of the same spine model referred to in FIG. 3after biomechanical testing of pedicle screw and intervertebral disccompression. This model demonstrates pedicle fractures as a result ofover-compression, similar to what was seen in the cadaveric studies thatFIG. 3 was modeled after.

Referring again to FIG. 7, the testing apparatus 404 is arranged toprovide a true axial force on the pedicle screw 403 as described herein.The duration, time, and type of testing may be controlled by the user ora computer algorithm per predetermined testing parameters that aregenerated for specific circumstances suitable for the user's needs.Devices such as the testing apparatus 404 implemented for conducting thetesting may be configured by the user or a computer algorithm, and cantake any form necessary to suite the user's preferences. In the instantnon-limiting embodiment, the vertebra body model 402 is disposed betweenthe jaws 408A and 408B of the vise grip 406 and a top portion 409 of thepedicle screw 403 and/or the vertebra body model 402 is configured toattach or otherwise engage to a carabiner 410 such that a user may exertexternal force on the pedicle screw 403 and/or the vertebra body model402 to test its resistance to changes in pressure, force, angle, andother factors that may be mirrored by its use in the patient's spine. Itis of course contemplated that other testing may be undergone, such asradiation testing, kinematics testing, and any other testing that wouldsuit the user's preferences. The instant non-limiting method of thedisclosure may also be used on animal parts, or non-living components.For example, it is contemplated that a spine of a canine may be used intesting, training, and demonstration.

FIG. 10 illustrates a 3D printed vertebral body model 420 withpre-determined cannulation trajectories 422 of the vertebral pedicle.This eliminates variability in the trajectory of pedicle screws, andthereby reduces the variability in biomechanical testing achieved whenusing the synthetic models. Consequently, this model demonstrates asignificant advantage over cadaveric vertebral bodies or other syntheticbone and spine models. FIG. 11 illustrates a synthetic vertebral bodymodel that is being printed to include pedicle cannulation trajectories.This image also demonstrates how the models are printed to mimic thecorticocancellous architecture of human bone, with a thick corticalouter shell, and a thinner mesh filing the interior of the model. Thisarchitecture provides both high fidelity radiographic anatomy of themodel under standard fluoroscopy and computed tomography, enablescertain physiological functions such as bleeding of the bone (aftermodification are made post-printing), and improves the biomechanicalperformance of the bone as it more closely mimics the architecture ofhuman bone.

Experimentally Derived Datasets 112

As described, the experimentally derived datasets 112 are informative asto suitable configurations for printing materials and print parametersto print anatomical models with predetermined properties. Substantialresearch and testing was conducted to arrive at the experimentallyderived datasets 112. Specifically, for example, at least one study wasconducted to describe the biomechanical performance of athree-dimensional (3D)-printed vertebra on pedicle screw insertionaltorque (IT), axial pullout (APO), and stiffness (ST) testing.Seventy-three anatomically identical L5 vertebral body models (146pedicles) were printed and tested for IT, APO, and ST usingsingle-threaded pedicle screws of equivalent diameter (6.5 mm), length(40.0 mm), and thread pitch (2.6 mm). Material, cortical thickness(number of shells), cancellous density (in-fill), in-fill pattern, andprint orientation were varied among the models. One-way analysis ofvariance was performed to evaluate the effect of the variables on theoutcomes.

SUMMARY

During the study, it was found that the type of printing materialsignificantly affected IT, APO, and ST (P<0.001 for all comparisons).For acrylonitrile butadiene styrene (ABS) models, in-fill density(25-35%) had a positive linear association with APO (P=0.002), ST(P=0.008), and IT (P=0.10); similarly for the polylactic acid (PLA)models, APO (P=0.001), IT (P<0.001), and ST (P=0.14). For the nylonmaterial type, in-fill density did not affect any tested parameter. Fora given in-fill density, material, and print orientation, the in-fillpattern had a significant effect on IT (P=0.002) and APO (P=0.03). Printorientation also significantly affected IT (P<0.001), APO (P<0.001), andST (P=0.002). The 3D-printed vertebral body models made of ABS and PLAperformed analogously to human bone on pedicle screw tests of IT, APO,and ST. By altering the material, in-fill density, in-fill pattern, andprint orientation of the synthetic vertebral body models, one couldreliably produce a model that mimics bone of a specific bone mineraldensity.

Detailed Testing and Analysis

Additional details regarding the research and testing associated with a3D-printed spine model, which contributed at least in part to theformation of the experimentally derived datasets 112, shall now bedisclosed. Leveraging this research and the experimentally deriveddatasets 112, a synthetic spine model was eventually formed withsynthetic bone material that mimics human bone in its corticocancellousarchitecture and its biomechanical performance on screw insertionaltorque (IT), axial pullout (APO) force, and stiffness (ST) testing. Themodel demonstrated expected changes in these biomechanical performancemeasures when printed to mimic human bone of higher or lower BMD.

As part of preliminary analysis, a high-resolution computed tomogram(CT) of a normal lumbar spine was segmented and converted into a 3D fileusing Materialise Mimics software (Materialise, NV, Leuven, Belgium). Acomplete L5 vertebra was extracted from this 3D file and converted to astereolithography (.stl) file format. The .stl file was imported intothe Simplify3D software package (Simplify3D, LLC, Blue Ash, Ohio, USA).A plurality of L5 vertebra models (“models”) were then printed using aFlashForge Creator Pro.

During and after formation, the models were used to evaluate various 3Dprint settings suitable for a synthetic spine, including settingsassociated with base materials for 3D printing. By non-limiting example,the models were printed using three different materials: acrylonitrilebutadiene styrene (ABS), polylactic acid (PLA), and nylon. ABS is acommon thermoplastic polymer that is petroleum-based and known for itsimpact resistance and durability. PLA is a biodegradable and bioactivethermoplastic derived from sugar-based substances (e.g., cornstarch,sugarcane, cassava root). PLA has a much lower glass transitiontemperature than ABS and is more brittle, but it also has higher impactresistance and toughness. Nylon is a family of thermoplastic syntheticpolymers. Nylon 230 may be implemented because it has a much lower glasstransition temperature (230° C.) than other types of nylon. 3D-printednylon is known for its high durability, strength, and versatility inthat thin layers of printed nylon remain very flexible whereas thicklayers become rigid and stiff.

Other evaluated 3D print setting variables included print shell, in-fillpercent, in-fill pattern, and print orientation, and the like. The3D-printed L5 vertebral body models were printed with a dense outerlayer of plastic (called the “shell”) and a much less dense innercomponent (called the “in-fill”), analogous to the cortical andcancellous structure of human bone, respectively. FIGS. 12-13demonstrate the shell and in-fill of a vertebral body model (FIG. 12),and how this structure mimics the cortiocancellous architecture of humanbone when viewed under fluoroscopy (FIG. 13). It was discovered thatboth the shell and the in-fill can be modified to print at variousthicknesses and densities. The in-fill can furthermore be modified to beprinted in one of several different patterns, including hexagonal,diamond, and linear.

In one example study, a number of printer settings were held constantfor all models printed with a specific material. For the ABS models, theprint temperature was held at 240° C., the print bed temperature at 110°C., the print resolution at 0.2 mm, and the print speed at 60 mm/s. ForPLA, the print temperature was held at 230° C., the print bedtemperature at 30° C., the print resolution at 0.2 mm, and the printspeed at 60 mm/s. For nylon, the print temperature was held at 230° C.,the print bed temperature at 50° C., the print resolution at 0.2 mm, andthe print speed at 30 mm/s. These printer settings were not tested fortheir effect on the biomechanical performance of the model; they werekept constant across all models printed with the same material in orderto avoid any error introduced by variation in these settings.

Historical Results for Comparison

To validate the vertebral body model's utility as a synthetic bonesubstitute in biomechanical testing, historical data on cadaveric andliving bone was referenced. Historical data included, e.g., comparisonof the performance of a single-threaded vs a dual-threaded screw on IT,APO, and ST testing. This information was leveraged to implement similarmethods to test the L5 synthetic vertebra models, using single-threadedscrews of equivalent diameter (6.5 mm), length (40.0 mm), and threadpitch (2.6 mm). Screw insertion, IT, APO, and ST testing were allperformed on the L5 synthetic vertebra models in order to permit ameaningful comparison of the results they generated using cadaveric bonewith the results generated in this study using the synthetic L5 vertebramodels. All equipment used in for this study during IT, APO, and STtesting was the same or similar equipment used by Brasiliense et al., asthese studies took place in the same laboratory.

Study Design

Seventy-three L5 vertebral body models (146 pedicles) were printed fromthe same .stl file such that all the models were anatomically identical.ABS, PLA, and nylon models were printed with a shell density rangingfrom 1-8 shells, and an in-fill density ranging from 10%-50%. Modelswere also printed with different in-fill patterns (hexagonal vs. linearvs. diamond), and different orientations on the print bed (horizontalvs. vertical print alignment). FIG. 14 and FIG. 15 demonstrate thedifference between models printed with horizontal print alignment andvertical print alignment. Horizontal and vertical refer to the z-axis ofthe 3D printer in relation to the anatomical top and bottom of the L5vertebra. When the model is printed in the horizontal orientation (FIG.14), layers of plastic filament are placed on top of each other from thebottom to the top of the vertebral model. In the vertical orientation(FIG. 15), filament layers are parallel to the top and bottom of thevertebra, and are stacked from the ventral vertebra to the dorsalvertebra.

Each model was subjected to pedicle screw insertion of the bilateralpedicles using a 6.×40.0 mm screw with a single thread pitch of 2.6 mm.A tester inserted all the pedicle screws to minimize differences inpedicle screw trajectory between the models. To avoid bias, this testerwas blinded to the torque values. During pedicle screw insertion, atorque sensor measured and collected the IT at a rate of 5 Hz. Afterbilateral pedicle screws were inserted in the models, they were placedin a metal fixture and potted in a casting mold of polymethylmethacrylate.

After the vertebral bodies were potted, a uniaxial servohydraulic testframe (858 Mini Bionix, MTS Test Systems Corp., Eden Prairie, Minn.,USA) was used to conduct APO testing of each pedicle screw. In summary,an angle vise was used to affix the polymethyl methacrylate mold of eachmodel to the base of the testing apparatus. The long axis of the pediclescrew to be tested was then aligned parallel to the axis of the testingapparatus in order to create a pure axial force vector on each pediclescrew. APO loading force was at a 10 mm/min displacement rate. Loadversus displacement data were continuously recorded at a frequency of 10Hz until total screw failure, which was defined as the point on theload-displacement curve at which a precipitous decline occurs. APO wasthen calculated as the greatest load prior to failure. Theload-displacement curve was then used to calculate the screw ST, whichwas defined as the steepest slope on the load-displacement curve.Referring back to FIG. 7, the illustration shown demonstrates avertebral body model undergoing such an APO test.

Statistical Analysis

Descriptive statistics, including means and standard deviations, werecollected for all models. The D'Agostino-Pearson normality test was usedto determine the normalcy of the data. Left and right pedicles werecompared separately and together. One-way analysis of variance (ANOVA)tests were performed to evaluate for the effect of material, shelldensity, in-fill density, in-fill pattern, and print pattern on themeasured outcomes.

Results

Thirty-seven ABS models were printed and underwent complete testing.These models had shell density ranging from 1 to 8 shell layers, in-filldensity ranging from 10 to 50%, 3 different in-fill patterns (hexagonal,linear, diamond), and both horizontal and vertical print orientations.Twenty-seven PLA models and 27 nylon models were printed, all with ashell density of 4 or 8 layers and an in-fill density of 25%, 30%, or35%.

IT, APO, and ST tested values were normally distributed(D'Agostino-Pearson normality test, P>0.05 for all). In the analysis ofall tested variables from all different material types, shells,in-fills, in-fill patterns, and orientations, no significant variancewas found between pedicles on the left versus the right side for IT,APO, and ST (P>0.05 for all).The type of material significantly affectedIT, APO, and ST (P<0.001 for all comparisons). FIG. 16 provides a boxplot summary of the effect of material type on the tested parameters.The left box plot summary shows the effect of material type on axialpull-out (APO) testing; the middle box plot summary shows the effect ofmaterial type under stiffness (ST) testing; and the right box plotsummary shows the effect of material type on insertional torque (IT)testing.

PLA demonstrated the highest IT, APO, and ST values, followed by ABS andnylon, respectively. For the ABS models, in-fill density (25-35%) had apositive linear association with APO (P=0.002), ST (P=0.008), and IT(P=0.10). For the PLA models, APO (P=0.001), IT (P<0.001), and ST(P=0.14) had a similarly positive linear association with in-filldensity. For the nylon material type, in-fill density did not affect anytested parameter. FIG. 17 provides a box plot summary of the effect ofin-fill on the tested parameters for models of all 3 material types:(Top row) Effect of in-fill on APO for ABS, Nylon, and PLA models;(Middle row) Effect of in-fill on ST for ABS, Nylon, and PLA models; and(Bottom row) Effect of in-fill on IT for ABS, Nylon, and PLA models.

For a given in-fill density, material, and print orientation, thein-fill pattern had a significant effect on IT (P=0.002) and APO(P=0.03) but not on ST (p=0.23). Print orientation also significantlyaffected IT (P<0.001), APO (P<0.001), and ST (P=0.002). Shell densitydid not significantly affect the biomechanical performance of thesynthetic bone models.

Discussion of Results

Nylon does not appear to be a good material for a synthetic bone model,as changes in the evaluated print parameters did not result inpredictable changes in the tested outcomes. ABS and PLA, however,demonstrated good correlation between model in-fill density andbiomechanical performance measures, and as such both are good candidatematerials for use in a synthetic lumbar vertebral body model.Interestingly, PLA models had significantly greater IT, APO, and STvalues than ABS models. Anecdotally, however, the ABS models felt muchmore similar to human bone than the PLA models when cannulating thepedicles and placing pedicle screws. Specifically, the PLA did not breakor deform under the pressure of a pedicle-finding probe, but ratherbecame somewhat soft. This observation may be explained by the muchlower glass transition temperature of PLA (60° C.) as compared to ABS(105° C.); the friction generated by twisting a pedicle-finding probe orinserting a pedicle screw into the PLA model likely causes the model todeform locally rather than break. On the other hand, ABS would readilybreak when contacting a twisting pedicle probe, creating a feeling verysimilar to that of human bone. Given that the ABS and PLA modelsappeared to perform with equivalent reliability in terms of their linearassociations between print variables and tested outcomes, it is believedthat ABS is the most promising of these 3 materials tested for furtherdevelopment and use as a synthetic model of a lumbar vertebra.

Also significantly impacting the tested outcomes were in-fill patternand print orientation. Interestingly, in-fill pattern predictablyimpacted all 3 tested outcomes, with the diamond pattern producinghigher IT, APO, and ST values than the hexagonal and linear patterns.This finding will be important when selecting specific print parametersfor the creation of synthetic vertebral body models that will beinstrumented, as the choice of in-fill pattern will significantly impactthe screw performance in those models. Similarly, the print orientationhad a highly significant impact on the tested outcomes, although thedirection of effect was different for IT than for APO and ST. Thisfinding likely relates to the observation that the models tended to failon APO testing in a plane parallel to the print orientation. The IT wasmeasured during screw insertion, whereas the APO and ST were measuredduring screw pullout. The impact of the print orientation is thereforelikely to impact the tested outcomes differently during these tests.

For the ABS models, in-fill had a significant effect on IT and APO butnot on ST. Similarly, in-fill pattern significantly affected IT and APObut not ST. However, ST was significantly different among vertebral bodymodels of different material. Perhaps this finding indicates that ST ismore affected by material type than the other tested outcomes.

Comparison to Historical Data

By using the linear regression analysis correlating APO and BMD that waspublished, BMD likely to mimic can be predicted with certain modelmaterials and print settings. Nylon, for example, had a mean (SD) APOforce of 223 (103) N; using the Halvorson et al. linear regression, thisvalue correlates with a BMD<0.6 g/cm². A BMD value this low representsextreme osteoporosis and falls off the normal curve entirely. On theother hand, the mean APO force for ABS (1104 N) and PLA (2713 [684] N)models would correlate with a BMD of approximately 1.0 g/cm² and >1.4g/cm², respectively. The same type of comparisons to historic data canbe performed for IT and ST. Previous studies correlating BMD with IT andST show that the studied synthetic model produces IT and ST valuessimilar to those described in these historical data and that thesevariables can be reliably predicted through changes in the modelmaterial, in-fill density, and in-fill pattern.[11-14] Thus, it is easyto imagine the studied synthetic models being printed to performanalogously on IT, APO, and ST to human bone of a specific BMD. Thesemodels have potential, therefore, to become promising new platforms forspine biomechanics research. Furthermore, this study validates theircontinued use as synthetic bone in our continued efforts to 3D print asynthetic spine model with high anatomical, radiographic, andbiomechanical fidelity to human tissue.

Future Considerations

Since the present study was conducted, a synthetic vertebral body modelwas developed that includes a standard pedicle trajectory printed intoit. Similar testing is planned to test IT, APO, and ST in this model todetermine whether this modification decreases the variability of resultsamong models.

Testing of spinal segment range of motion has also been conducted in asimilar fashion to determine the best print parameters of soft tissuecomponents to achieve a synthetic spine model that mimics the humanspine in range of motion and compression testing.

Testing Conclusions

The 3D-printed vertebral body models made of ABS and PLA performedanalogously to human bone on pedicle screw tests of IT, APO, and ST. Byaltering the material, in-fill density, in-fill pattern, and printorientation of the synthetic vertebral body models, one could reliablyproduce a model that mimics bone with a specific BMD. As such, thesesynthetic models represent a promising new tool in spine biomechanicsresearch, and they have promising potential utility in the fields ofsurgical planning and surgical education.

Additional Synthetic Components and Other Embodiments

Many additional synthetic anatomical components and additionalembodiments and features are contemplated in view of the abovedescription. For example, in one non-limiting embodiment, the syntheticanatomical model 116 may comprise a plurality of connecting portsdisposed between adjacent vertebral segments and positioned on theinterior surface of the vertebral segments, on the exterior surface ofthe vertebral segments, or a combination of both. At least one of theseconnecting ports may be configured to accommodate and releasably engagesurgical tubing to one or more vertebral segments by any mechanism orstructure or by any method or process suitable for, and capable of,maintaining or securing the surgical tubing in the desired position. Forexample, the synthetic anatomical model 116 may be printed with aplurality of connecting ports that can receive the surgical tubing whichand held in a coaxial position by an adhesive or by predetermining theposition of the plurality of connecting ports and the surgical tubingand configuring the diameter of the plurality of connecting ports insuch a manner that the fitting between the plurality of connecting portsand surgical tubing restrains the surgical tubing from unwantedmovement. It should be considered that surgical tubing is intended toread as any substantially flexible or rigid tubing suitable fortransferring liquids, gases, semi dissolved solids, or any combinationof these, used in the medical field. In this embodiment, the pluralityof connecting ports and the surgical tubing may be adapted or designedto contain and carry any material, liquid, or substance capable offorming artificial blood. For example, FIG. 18 illustrates an exemplaryprinted anatomical model 516 outfitted with such connecting ports 518and surgical tubing 520 integrated to the printed anatomical model 516to simulate bleeding bone. In FIG. 18, the depicted bone is being bittenwith a rongeur, and artificial blood 522 is seen spilling from theprinted anatomical model 516 (through a connecting port, not shown). Inthis example, in one non-limiting embodiment, the artificial blood maybe comprised of water or another similar aqueous solution and a redcolor additive (and possibly other ingredients) in order to closelyreplicate the consistency and aesthetics of a patient's blood.

As indicated in block 214 of FIG. 2A, in some non-limiting embodiments,the testing procedures may include drilling into or through a portion ofthe synthetic anatomical model 116 in order to separate the lamina fromthe rest of the vertebral segment, or to create pilot holes for pediclescrew insertion. In this non-limiting embodiment, the vertebral segmentsof the synthetic anatomical model 116 may comprise the plurality ofconnecting ports 518 and the surgical tubing 520 which contains theartificial blood 522 and mimics cadaveric bleeding when punctured by thetester's surgical tool. Thus, the plurality of connecting ports 518 maysimulate a synthetic or artificial circulatory system that hemorrhagessimilar to a natural circulatory system.

In another non-limiting embodiment, the surgical tubing 520 describedmay be connected to an external pump (not shown) and artificial bloodsource (not shown) such that the artificial blood may be pumped to, andthrough the external pump and then through the surgical tubing toemulate a patient's natural circulatory system. It is considered thatthe artificial blood source may be any container or receptacleconfigured for and capable of storing the artificial blood. Thisoperation can further be controlled by a series of valves (not shown)configured to control the flow of the artificial blood through thetubing and synthetic anatomical model 116. These valves may be used tocreate pockets of pressurized areas within the synthetic anatomicalmodel 116 to impede the flow of artificial blood to specific areas.

In yet another non-limiting embodiment, the synthetic anatomical model116 may further include an artificial soft tissue layer, illustrated assoft tissue layer 524 of FIG. 18, overlaying the synthetic model suchthat the synthetic anatomical model 116 is completely or partiallydisposed within the artificial soft tissue layer 524. In thisnon-limiting embodiment, the artificial soft tissue layer 524 mayinclude e.g., Styrofoam, or may be comprised out of any material orsubstance suitable for the tester's preference without departing fromthe scope of this disclosure. For example, it is considered that thesoft tissue layer 524 may be comprised of some flexible or inflexiblematerial such as a silicone, rubber, elastomeric polymer, foam, orcombinations thereof. Moreover, the artificial soft tissue layer 524 maycomprise multiple segments of varying thickness, density, and chemicalproperties. In essence, the artificial soft tissue layer 524 mayfunction to provide not only the major structural and physicalcharacteristics of human soft tissue, but any structure and physicalcharacteristics of the human body that may be suitable for the testingprocedure. Thus, dural layers, cartilage, bone, ligaments, ancillarytissue may all be formed as part of the soft tissue layer 524 of thehigh fidelity synthetic anatomical model 116.

In yet another non-limiting embodiment, the synthetic anatomical model116 can be constructed with a synthetic thecal sac 532, as illustratedby a synthetic anatomical model 530 shown in FIG. 19, configured to havea tubular structure that reflects a patient's anatomical proportions andconstructed out of any material or substance suitable for the testingprocedure that mimic's a patient's thecal sac without departing from thescope of the disclosure. To illustrate, it is considered that the thecalsac 532 may be comprised out of any transparent or colored polymer,silicone, rubber, wax, resin, collagen, or any combinations thereof.Furthermore, the material may also be substantially impermeable to wateror other liquid solutions in order to prevent unwanted permeation of theliquid solution throughout the synthetic anatomical model 116. In thisarrangement, the thecal sac 532 may be completely or partially hollow tocomprise an interior portion (not shown) such that the interior portionmay be completely or partially filled with water or another liquidsolution that mimics cerebrospinal fluid. When a non-limiting embodimentlike this is adopted, the interior portion may have a pressurizedenvironment such that liquid solution can mimic the cerebrospinal fluidinside a patient's thecal sac to a relatively high degree of fidelity.To illustrate, during the testing procedure the thecal sac 532 can beused for practicing surgical procedures such as a laminectomy. In thisinstance, if the underlying thecal sac is punctured during the test,internal pressure from the synthetic anatomical model 116 will force theliquid solution through the punctured portion of the model where it willbe visible by the surgeon; the surgeon may then practice repairing thethecal sac 532 in accordance with general durotomy procedures. Thethecal sac 532 can also contain certain materials that mimic the spinalcord and/or nerve roots, to increase the face validity of the syntheticmodel as a surgical training platform. In addition, the thecal sac 532described may be configured to attach to the synthetic anatomical model116 by any mechanism or structure or by any method or process suitablefor, and capable of, maintaining or securing the thecal sac 532 in adesired position. For example, the synthetic thecal sac 532 and thesynthetic anatomical model 116 may be each printed as a separatecomponent and combined together using an adhesive agent or similarcomponent. The thecal sac 532 can alternatively be constructed in anon-3D printing process and added to the synthetic anatomical model 116.In the specific example of FIG. 19, the thecal sac 532 is composed ofsynthetic collagen which is added to the synthetic anatomical model 530after printing. The thecal sac 532 may be connected to a source of fluidthat mimics cerebrospinal fluid, so that when the thecal sac 532 isinjured (e.g., penetrated or ruptured), the thecal sac 532 may leakfluid under pressure to mimic operative conditions.

In yet another non-limiting embodiment, the thecal sac 532 described mayalso comprise at least one pressure sensor (not shown) that detectssignals from an external force applying pressure and transmits thatsignal to a receiver (not shown). The specific signal transmittingmethods may comprise any communications link, method, or processsuitable for detecting the external signal, including a transmitter,transceiver, controller, processor receiver and a means for displayingthe external signal to the surgeon as well as a power source (not shown)that is configured to be coupled with the at least one pressure sensorand may supply the at least one pressure sensor with sufficient power tomaintain operation. To illustrate this non-limiting embodiment, theexternal signal may be displayed to the surgeon through an externaldisplay screen (not shown) of a personal computer. In the event thatthere is more than one pressure sensor, each sensor may have a differentposition and orientation within the synthetic anatomical model 116 thatmay be useful for the specific testing procedure. For instance, thesensor or a network of sensors may be placed within the thecal sac 532at various locations to correspond with the relative position of thevertebral segments that are to be removed by the surgeon. In accordancewith this non-limiting embodiment, the training procedure may requireaccurate tracking of the surgeon's movements to avoid real lifeinstances of a durotomy caused by the surgeon's tool piercing the thecalsac 532 and/or the underlying layers. As such, the sensor may beintegrated into the synthetic anatomical model 116 to provide thesurgeon with an accurate measurement of the position of the surgeon'stool within the synthetic anatomical model 116 which may then betransferred through a communications link to a display (not shown). Inthis case, the tool may be any type of medical tool suitable for thisprocedure, such as a high-speed drill, scalpel, etc. The at least onesensor may be calibrated to the surgeon's preference prior to or duringthe testing procedure.

In yet another non-limiting embodiment, the pressure sensor may beconfigured to directly elicit an auditory or visual signal whenactivated so that it provides the surgeon with real-time feedback on thelocation of the surgeon's tool within the synthetic anatomical model116. For example, at least one pressure sensor may be positioneddirectly beneath the lamina and on the dural layer of the syntheticanatomical model 116 such that when the surgeon's tool strikes thesensor, it will immediately elicit an auditory signal alerting thesurgeon to the position of their surgical tool. In still othernon-limiting embodiments, the at least one pressure sensor may beconfigured to couple with at least one optical component (not shown)integrated into the synthetic anatomical model 116 and positioned alongor in the device in any method that is suitable for the testingprocedure and to the user's preference. In this non-limiting embodiment,when the at least one pressure sensor is activated, it will send asignal to the optical component which elicits an illuminatory response,allowing the surgeon to observe the signal response in real-time. Forexample, in this non-limiting embodiment, the synthetic anatomical model116 may have an LED or series of LEDs (not shown) embedded within thedevice, but within the surgeon's view, such that when the surgeon's toolstrikes the pressure sensor (not shown), the LED is illuminated andallows the surgeon to correct their technique.

In another embodiment, the synthetic anatomical model 116 may beconstructed with neural elements and/or conductive nerve roots. FIG. 20,for example, illustrates a synthetic anatomical model 540 of L3-L5segments with synthetic neural elements 542 formed using a thermoplasticmixed with graphite that enables it to conduct electricity after being3D printed. FIG. 21 illustrates a synthetic anatomical model 550 withsynthetic conductive nerve roots 552 formed using leads or conductivewires/layers configured to conduct electricity through or around thesynthetic anatomical model 550 after the synthetic anatomical model 550has been printed. FIG. 22 illustrates a synthetic anatomical model 560of an L1-pelvis with electrically conductive neural elements 562 in theform of copper wire (but may also be embodied with other conductivematerials). In this embodiment, the synthetic anatomical model 560includes 3D printed bone 564, 3D printed anterior longitudinal ligamentand intervertebral discs 566, and psoas muscle 568. The electricallyconductive neural elements 562 run from the spinal canal 570 through thepsoas muscle 568 in the same trajectory as anatomically seen in humans.In this example, a surgeon may apply an electrical stimulus with a metalprobe, and when the probe begins to approach one of the simulatedelectrically conductive neural elements 562, the surgeon may be alertedas to the presence of a nerve root (by an audio or visual stimulus).This enables simulation of operative conditions and provides the samephysiological feedback that a living human spine would provide asurgeon.

In another non-limiting embodiment illustrated by the syntheticanatomical model 580 of a cervical spine shown in FIG. 23, the syntheticanatomical model 116 may be formed with vertebral arteries 582 thatbleed if injured or ruptured. In this example, the synthetic anatomicalmodel 580 further includes 3D printed synthetic bone 584, and syntheticligamentous structures 586. The vertebral arteries 582 may be formedusing collagen sacs, and may also incorporate aspects of FIG. 18including the plurality of connecting ports 518 and the surgical tubing520 used to distribute artificial blood through the model.

In another non-limiting embodiment illustrated by the syntheticanatomical model 600 of a cervical spine shown in FIG. 24, radiolucentsoft tissue made of foam may be formed along the synthetic anatomicalmodel 116. In this example, the synthetic anatomical model 600 alsoincludes 3D printed synthetic bone 604, synthetic ligamentous structures606, and a synthetic thecal sac 608.

In another non-limiting embodiment illustrated by the syntheticanatomical model 620 (L3-L5 spinal model) of FIG. 25, the syntheticanatomical model 116 may further be constructed with a syntheticligamentum flavum 622 oriented in the interlaminar space which may beformed after 3D printing of synthetic bone material 624 shown. FIG. 25further shows another example of a synthetic thecal sac 626.

In another non-limiting embodiment illustrated by the syntheticanatomical model 640 (L3-L5 spinal model) of FIG. 26, the syntheticanatomical model 116 may further be constructed with a syntheticperiosteum tissue layer 642 positioned over the spinous processes of L3and L4 which may be formed or added after 3D printing of synthetic bonematerial 644 as shown. The synthetic periosteum tissue layer 642 may beformed using collagen or other similar material and may be added after3D printing of the synthetic bone material 644.In another non-limitingembodiment, the synthetic anatomical model 116 or any of the syntheticanatomical components described may be directly implanted within asubject, or use for testing. It is also contemplated that the componentmay be printed directly into the subject's anatomy without departingfrom the scope of the disclosure. It is also contemplated that theprinted or artificial anatomical components of the present inventiveconcept are capable of biodegradation, bioabsorbtion, or both, whetherit is being used as a temporary implant, or for another purpose suitablefor the user's needs. To illustrate, it is contemplated that thesynthetic anatomical model 116 may be constructed out of a degradable orabsorbable material such that it may act as a temporary supportstructure in the subject's body, thereby improving biomechanicalstability of other constructs. Indeed, the synthetic anatomical model116 could be printed to include or carry biological agents such as bonegraft extenders, bone morphogenic proteins, or other suitable agents.

In another non-limiting embodiment illustrated in part by the syntheticanatomical model of a knee in FIGS. 28A-B, a base 800 or frame may beconstructed to hold or otherwise support the synthetic anatomical model.The base 800 is constructed to securely hold the synthetic anatomicalmodel 600 and/or guide movement of the synthetic anatomical model in arange of motion that is biomechanically tested and reflects the range ofmotion of human subjects. The base may be formed using a polymeric resinor other materials such as wood, metals, and composites and the like.The base may include moving rail systems to facilitate natural movementand locking mechanisms to hold the synthetic anatomical model in aspecific orientation with a goal of stabilizing the synthetic anatomicalmodel for surgical instrumentation or inspection. For example, FIG. 28Aillustrates synthetic anatomical model 600 in the form of leg bones 810and a knee 820 in an extended position, while FIG. 28B illustratessynthetic anatomical model 600 after moving one end of the leg bones 810which has been connected to hinged slide assembly 830 that can slidealong a track 840 to a flexed position. In alternative configurations,bases and frames for other synthetic anatomical models of other physicalanatomy may be constructed to hold or otherwise support that particularsynthetic anatomical model and to guide the movement of that particularanatomy.

In some embodiments, different configurations of 3D printer filamentmaterials and printing parameters (based on the experimentally deriveddatasets 112) may be used to print different types of human tissue inthe spinal column (including, but not limited to, cortical bone,medullary bone, annulus fibrosus, nucleus pulposus, anteriorlongitudinal ligament, posterior longitudinal ligament, ligamentumflavum, interspinous ligament, supraspinous ligament, facet joint andcapsule, blood vessels, spinal cord and nerve roots, dura, andmuscle/muscle attachments). These materials may be printed eitherdirectly into each other, printed individually and later assembled, orconstructed separately through a combination of additive manufacturingand other manufacturing processes (i.e. silicone rubber or foam pouring)and then later added together.

In some embodiments, one or more portions of the synthetic anatomicalmodel may further include a coating that enhances the model'sbiomechanical, fluoroscopic, and surgical handling characteristics. Forexample, synthetic anatomical models created using filament depositionmodeling technologies can be prone to cracking and splitting alonglayers of 3D printed material. This splitting negatively impacts thebiomechanical and surgical handling performance of the syntheticanatomical model. For example, FIG. 29A illustrates distinct layers 900post-printing, prior to application of a coating, which may be prone tosplitting.

By treating the synthetic anatomical model with a solvent afterprinting, either by direct application of a liquid solvent or exposureof the synthetic anatomical model to an aerosolized or gaseous form ofthe solvent, the external layers of the synthetic anatomical model areessentially “melted” and better fused together. As seen in FIG. 29B,after application of the coating, the layers 900 are less distinct andmore strongly fused together. Such treatment of the synthetic anatomicalmodel with a solvent in this fashion helps prevent model splitting andcracking and improves both biomechanical performance and surgicalhandling of the synthetic anatomical model. Coatings can also include,but are not limited to, paints, adhesives, and sprays. Certain coatingscan also be applied to improve the fluoroscopic performance of thesynthetic anatomical model. For example, coating the bony components ofthe synthetic anatomical model with a zinc-containing paint will improvethe fluoroscopic appearance of the bony components of the syntheticanatomical model. Examples of solvents that may be applied to thesynthetic anatomical include 3D Gloop!, acetone (vapor or liquid) andthe like.

In some embodiments, aspects of the synthetic anatomical model 116 maybe printed with bony elements that are 3D printed using materials thatare similarly radio-opaque to bone such that fluoroscopic and X-rayimages can be taken of the model in a similar fashion to cadavericspecimens or living patients with similar results.

In some embodiments, utilizing functionality described herein, thesynthetic anatomical components may include soft tissue elements such asannulus fibrosus, nucleus pulposus, anterior longitudinal ligament,posterior longitudinal ligament, ligamentum flavum, interspinousligament, supraspinous ligament, facet joint and capsule, blood vessels,spinal cord and nerve roots, dura, and muscle attachments) that may be3D printed according to the experimentally derived datasets 112 andconfigured print parameters (including, but not limited to, printshells, in-fill percentage, filament material, extruder temperature,print orientation, and in-fill pattern) to biomechanically perform in apredictable and reliable fashion that closely approximates apre-determined healthy or diseased state.

In some embodiments, the synthetic spine model 116 may be constructedwith soft tissue elements (including, but not limited to, annulusfibrosus, nucleus pulposus, anterior longitudinal ligament, posteriorlongitudinal ligament, ligamentum flavum, interspinous ligament,supraspinous ligament, facet joint and capsule, blood vessels, spinalcord and nerve roots, dura, and muscle attachments) that are 3D printedusing a material that is similarly radio-opaque to human soft tissuesuch fluoroscopic and X-ray images can be taken of the model in asimilar fashion to cadaveric specimens or living patients with similarresults.

The synthetic spine model 116 and other synthetic components describedherein may be useful for many different applications. For example, thesynthetic spine model 116 may reduce the variability of biomechanicaltesting results when using the method of FIG. 2A, as the model and eachsubsequently constructed model may be nearly identical to others createdto the same parameters, thereby reducing the variability between modelswhich is so common in cadaveric testing. The synthetic spine model 116and other synthetic components may further be useful as a surgicalskills training modality for spine surgeons and other trainees. There isa national push for the development of synthetic training models inspecialized surgical fields, including spine surgery. For such models tohave worthwhile utility as a training tool, they must possess highanatomical and biomechanical fidelity to living patients. The presentmethod is capable of producing a synthetic spine model specific to anygiven patient's anatomy, with a biomechanical performance that can becustomized to cadaveric disease states. As another example, thesynthetic spine model 116 and other synthetic components may be usefulas part of a testing platform for spinal instrumentation. Commerciallyavailable technology and the prior art currently lacks a synthetic spinemodel that permits testing of spinal instrumentation in an anatomicallyand biomechanically fidelic model that can be customized to varioushealthy and diseased spine states. The present method could also be usedto create a model for use as a surgical planning tool for surgeons, ascustom models of individual patients' spines could be created and thenoperated on prior to the patient's actual surgery.

FIG. 27 is an example schematic diagram of a computing device 700 thatmay implement various methodologies discussed herein. For example, thecomputing device 700 may comprise the computing device 104 executing oraccessing functionality and/or aspects of the application 102. Thecomputing device 700 includes a bus 701 (i.e., interconnect), at leastone processor 702 or other computing element, at least one communicationport 703, a main memory 704, a removable storage media 705, a read-onlymemory 706, and a mass storage device 707. Processor(s) 702 can be anyknown processor, such as, but not limited to, an Intel® Itanium® orItanium 2® processor(s), AMD® Opteron® or Athlon MP® processor(s), orMotorola® lines of processors. Communication port 703 can be any of anRS-232 port for use with a modem based dial-up connection, a 10/100Ethernet port, a Gigabit port using copper or fiber, or a USB port.Communication port(s) 703 may be chosen depending on a network such as aLocal Area Network (LAN), a Wide Area Network (WAN), or any network towhich the computer device 700 connects. Computing device may furtherinclude a transport and/or transit network 755, a display screen 760, anI/O port 740, and an input device 745 such as a mouse or keyboard.

Main memory 704 can be Random Access Memory (RAM) or any other dynamicstorage device(s) commonly known in the art. Read-only memory 706 can beany static storage device(s) such as Programmable Read-Only Memory(PROM) chips for storing static information such as instructions forprocessor 702. Mass storage device 707 can be used to store informationand instructions. For example, hard disks such as the Adaptec® family ofSmall Computer Serial Interface (SCSI) drives, an optical disc, an arrayof disks such as Redundant Array of Independent Disks (RAID), such asthe Adaptec® family of RAID drives, or any other mass storage devices,may be used.

Bus 701 communicatively couples processor(s) 702 with the other memory,storage, and communications blocks. Bus 701 can be a PCI/PCI-X, SCSI, orUniversal Serial Bus (USB) based system bus (or other) depending on thestorage devices used. Removable storage media 705 can be any kind ofexternal hard drives, thumb drives, Compact Disc-Read Only Memory(CD-ROM), Compact Disc-Re-Writable (CD-RW), Digital Video Disk-Read OnlyMemory (DVD-ROM), etc.

Embodiments herein may be provided as a computer program product, whichmay include a machine-readable medium having stored thereon instructionswhich may be used to program a computer (or other electronic devices) toperform a process. The machine-readable medium may include, but is notlimited to optical discs, CD-ROMs, magneto-optical disks, ROMs, RAMs,erasable programmable read-only memories (EPROMs), electrically erasableprogrammable read-only memories (EEPROMs), magnetic or optical cards,flash memory, or other type of media/machine-readable medium suitablefor storing electronic instructions. Moreover, embodiments herein mayalso be downloaded as a computer program product, wherein the programmay be transferred from a remote computer to a requesting computer byway of data signals embodied in a carrier wave or other propagationmedium via a communication link (e.g., modem or network connection).

As shown, main memory 704 may be encoded with the application 102 thatsupports functionality discussed above. In other words, aspects of theapplication 102 (and/or other resources as described herein) can beembodied as software code such as data and/or logic instructions (e.g.,code stored in the memory or on another computer readable medium such asa disk) that supports processing functionality according to differentembodiments described herein. During operation of one embodiment,processor(s) 702 accesses main memory 704 via the use of bus 701 inorder to launch, run, execute, interpret, or otherwise performprocesses, such as through logic instructions, executing on theprocessor 702 and based on the application 102 stored in main memory orotherwise tangibly stored.

It should be understood from the foregoing that, while particularembodiments have been illustrated and described, various modificationscan be made thereto without departing from the spirit and scope of theinventive concept as will be apparent to those skilled in the art. Suchchanges and modifications are within the scope and teachings of thisinventive concept as defined in the claims appended hereto.

What is claimed is:
 1. A method, comprising: accessing imaging dataassociated with a reference anatomical component for modeling; utilizinga computing device and 3D printer in operable communication with thecomputing device, configured for: creating a 3D printing file from theimaging data, the 3D printing file defining parameters for printing apolymeric synthetic model of the reference anatomical component;adjusting the parameters of the 3D printing file according toexperimentally derived datasets associated with anatomical,physiological, and biomechanical properties specific to the referenceanatomical component; printing at least a portion of the polymericsynthetic model of the reference anatomical component using theparameters as adjusted; and coating a surface of the polymeric syntheticmodel with a solvent to enhance at least one of a biomechanical,fluoroscopic, and surgical handling characteristics of the polymericsynthetic model.
 2. The method of claim 1, wherein the imaging data isgenerated from multiple reference anatomical components from more thanone subject to created integrated imaging data.
 3. The method of claim1, further comprising applying at least one biomechanical test to thepolymeric synthetic model.
 4. The method of claim 3, further comprisingre-adjusting the parameters of the 3D printing file based on resultsassociated with the at least one biomechanical test applied to thepolymeric synthetic model.
 5. The method of claim 1, wherein thereference anatomical component is associated with a CT scan of apatient.
 6. The method of claim 1, wherein the experimentally deriveddatasets are derived at least based on biomechanical testing of apedicle screw relative to a spinal segment of a cadaver.
 7. The methodof claim 1, wherein the polymeric synthetic model is printed with afirst portion corresponding to a first configuration of print parametersand materials and a second portion corresponding to a secondconfiguration of print parameters and materials, the first portion andthe second portion simulating different portions of natural anatomy. 8.The method of claim 1, further comprising embedding the polymericsynthetic model at least partially within a synthetic soft tissue. 9.The method of claim 1, further comprising positioning a synthetic thecalsac along the polymeric synthetic model.
 10. The method of claim 1,wherein the polymeric synthetic model is printed with a portionsimulating a nerve element, the portion including a metal such that theportion is electrically conductive.
 11. The method of claim 1, furthercomprising positioning a plurality of conductive wires along thepolymeric synthetic model to represent nerve roots.
 12. The method ofclaim 1, further comprising: forming a plurality of channels through thepolymeric synthetic model; disposing a surgical tubing through theplurality of channels; and disposing an artificial blood solution withinthe surgical tubing under a pressure.
 13. The method of claim 1, whereinthe imaging data is derived from a CAD software package, and the imagingdata, and the computing device is configured to convert the imaging datato STL files.
 14. The method of claim 1, further comprising modifyingthe 3D printing file to adjust one or more features for the polymericsynthetic model.
 15. The method of claim 1, wherein the polymericsynthetic model is printed to mimic corticocancellous architecture ofhuman bone, the polymeric synthetic model including a mesh portionfiling an interior of the polymeric synthetic model and having a firstthickness, and the polymeric synthetic model further having a corticalouter shell of a second thickness greater than the first thicknesspositioned around the mesh portion.
 16. The method of claim 1, whereinthe polymeric synthetic model is printed with radio-opaque materialssuch that the polymeric synthetic model is visible under fluoroscopicand X-ray devices.
 17. The method of claim 1, further comprisingsimulating a spinal correction procedure by applying a spinal fixationconstruct to the polymeric synthetic model.
 18. The method of claim 17,further comprising identifying failure points of the referenceanatomical component based on the spinal correction procedure applied tothe polymeric synthetic model.
 19. The method of claim 1, furthercomprising securing the polymeric synthetic model at least partiallywithin a base that facilitates moving the polymeric synthetic modelthrough a range of motion and locking the polymeric synthetic model incertain anatomical orientations.